Type 1 and type 2 iodothyronine deiodinases in the thyroid gland of patients with huge goitrous Hashimoto's thyroiditis

Giant cervical goiter in Hashimoto's thyroiditis: A case report

A giant cervical goiter, defined as a thyroid mass larger than 8 cm in diameter, is usually a nodular or adenomatous goiter. A giant cervical goiter can also be caused by hyperthyroidism (i.e., Hashimoto’s thyroiditis). The surgical indications for patients with Hashimoto’s disease include suspected malignant tumors, persistent symptoms related to the disease, or persistent enlargement of the goiter. We herein describe a woman who developed symptoms of compression from a thyroid tumor, the volume of which was almost the largest reported in the relevant literature to date. The bilateral lobes of the giant thyroid tumor were removed by total en bloc excision. We protected the bilateral recurrent laryngeal nerve and preserved the bilateral upper and lower parathyroid glands in situ. The excised left lobe tumor was 16 × 9 × 5.5 cm, whereas the right lobe tumor was 12 × 8 × 4 cm. The pathological diagnosis was Hashimoto’s thyroiditis. Although surgical excision is difficult, it is still the main treatment modality for giant goiters in patients with Hashimoto’s thyroiditis and can help to reduce the occurrence of complications.

Poorly Differentiated Thyroid Carcinoma Coexisting with Graves' Disease Involving T3 Thyrotoxicosis due to Increased D1 and D2 Activities

Background: Poorly differentiated thyroid carcinoma is rare and patients are typically euthyroid. We report a novel rare case of poorly differentiated thyroid carcinoma with triiodothyronine (T3) thyrotoxicosis. Patient's Findings: A 77-year-old man presented to Kuma Hospital due to a neck tumor. A thyroid ultrasonography revealed a 220-mL mass in the right lobe. Laboratory data showed low serum thyrotropin (TSH), low free thyroxine (fT4), and high free T3 (fT3) levels. Anti-TSH receptor antibodies and thyroid-stimulating antibodies were positive. 131I scintigraphy showed diffuse uptake only in the left thyroid lobe. The patient underwent a total thyroidectomy and histological examination identified as poorly differentiated thyroid carcinoma. He was diagnosed with poorly differentiated thyroid carcinoma coexisting with Graves' disease. The tumor showed elevated type 1 iodothyronine deiodinases (D1) and type 2 iodothyronine deiodinases (D2) activities compared with that of the left thyroid lobe. Summary and Conclusions: Increased D1 and D2 activities in poorly differentiated carcinoma resulted in T3 toxicosis with a high serum fT3/fT4 ratio.

Association between serum thyroid hormone balance and thyroid volume in patients treated with levothyroxine monotherapy for hypothyroidism

Many previous studies including ours have reported that athyreotic patients on levothyroxine (LT₄) have relatively low serum free triiodothyronine (FT₃) levels, whereas patients with large goitrous diseases often have high serum FT₃ levels. Here we investigated Hashimoto thyroiditis (HT) patients on LT₄ to study the relationship between thyroid volume (TV) and thyroid hormone status in hypothyroid patients on LT₄. We retrospectively studied 408 euthyroid HT patients treated with LT₄ for hypothyroidism; divided them as per TV and compared serum levels of free thyroxine (FT₄) and FT₃ and the FT₃/FT₄ ratio in each patient group with those in euthyroid matched control group. We also evaluated the association between serum FT₃ level and FT₃/FT₄ ratio and TV among HT patients on LT₄. In patients with TV <15 mL, serum FT₃ levels were significantly lower than those in controls. In patients with TV 15-80 mL, serum FT₃ levels were equivalent to those in controls. In patients with TV ≥80 mL, the serum FT₃ levels were significantly higher than those in controls. The serum FT₃ level (r = 0.35, p < 0.01) and FT₃/FT₄ ratio (r = 0.42, p < 0.01) showed a positive correlation with TV. TVs in HT patients on LT₄ caused differences in serum thyroid hormone balance, as increasing volume increases the serum FT₃ level and FT₃/FT₄ ratio. Serum thyroid hormone balance in HT patients with smaller thyroids was similar to that in athyreotic patients. Mild thyrotropin suppression with LT₄ is needed to achieve normal FT₃ levels in such patients.

DAFS-25k impact on cattle’s thyroid hormonal status

The paper studies the impact of selenium organic preparation DAFS-25k on thyroid capacity in pregnant cows. A stud farm which the work is done in is a biogeochemical province distinguished by a sharp deficit of selenium and iodine in the diet. DAFS-25k had been implanted into the animals subcutaneously during 1 month 30 days before the predicted calving. A sterile 0.6 % DAFS-25k oil solution was used in doses containing 2 mg/cow/day, 6 mg/cow/day and 12 mg/cow/day. It was found that the cows’ diet is deficient in iodine and selenium by 63 and 82 % respectively. Daily use of selenium in DAFS-25k in the dose range causes a decrease in the concentration of free thyroxine due to deiodination activating by selenium dependent deiodinases of the first and second types. Consequently, there is a progressive increase in the blood content of total triiodothyronine in all experimental animals as relating to the background values. In this case, the concentration of thyroid-stimulating hormone decreases in blood serum by the 30th day according to the principle of negative feedback. In control animals, an increase in the serum concentration of thyroid-stimulating hormone reached the point 1.8 by the 30th day, total triiodothyronine increased by 14 and 19 % by the 21st day and the 30th day respectively, while the concentration of free thyroxine was reduced by 19 % by the 30th day. The use of selenium in the setting of iodine deficiency leads to aggravation of iodine deficiency.

The association between thyroid hormone balance and thyroid volume in patients with Hashimoto thyroiditis

While patients with large goitrous thyroid diseases often have a relatively high serum free triiodothyronine (FT₃)/free thyroxine (FT₄) ratio, athyreotic patients have a relatively low FT₃/FT₄ ratio. Here we investigated the relationship between thyroid hormone status and thyroid volume (TV) among a large number of euthyroid Hashimoto thyroiditis (HT) patients. We retrospectively enrolled 2,603 untreated HT patients who visited the Kuma hospital from 2012 to 2016, and divided them into four groups as per the TV: normal TV (<20 mL), slight goiter (20 ≤ TV < 50 mL), moderate goiter (50 ≤ TV < 80 mL), and the large goiter group (≥80 mL). Baseline characteristics and laboratory data of each group were compared to those of 1,554 control subjects. The association between FT₃/FT₄ ratio and TV among HT patients was then analyzed. We observed a change in laboratory parameters among 13 patients in the large goiter group who were prescribed levothyroxine (LT₄) for reducing TV. Compared to normal subjects, the moderate and large goiter groups exhibited significantly higher serum FT₃ levels, while all HT groups exhibited lower serum FT₄ levels. Serum FT₃/FT₄ ratios showed a positive correlation with TV (r = 0.35, p < 0.01), which was independent of age, sex, body mass index, and TgAb and TSH levels. LT₄ treatment lowered serum FT₃ levels and FT₃/FT₄ ratios significantly. Our results indicated that HT patients with increased TV tended to present with high serum FT₃, low FT₄, and high FT₃/FT₄ ratios. The elevation of deiodinase activity may be an important factor affecting thyroid hormonal balance in such patients.